The Chief Medical Officer of Pfizer has written to the British Medical Journal (BMJ) following the publication of a study1 that failed to find consistent evidence of enhanced safety with any of the new cyclo-oxygenase-2 (COX-2) inhibitors compared with non-selective non-steroidal anti-inflammatory drugs (NSAIDs).

The letter claims that the conclusions drawn in the study (discussed previously) do not reflect the evidence. However this letter has produced many responses that have pointed out the flaws in Pfizer's response.

One of the key points raised is that much of the data is based upon observational studies. This kind of study occupies a lower level on the hierarchy of evidence than controlled trials.

The only controlled trial for celecoxib was the CLASS Study2. In this study there was no significant difference between celecoxib and ibuprofen and naproxen in the primary outcome of gastrointestinal ulcer complications.

Action: The NSAID debate seems set to run for some time. However, the evidence is clear that paracetamol carries a lower overall risk of cardiac, renal and gastrointestinal problems in clinical use.